The present invention relates to intentionally induced hypo- or hyperthermia medical treatments. Specifically, the present invention is a method and device for inducing whole-body hypo- or hyperthermia while protecting the central nervous system to prevent neurological damage during the hypo- or hyperthermia procedure.
The normal body temperature in a human varies depending on a variety of factors but typically ranges between 36.1xc2x0 C. and 37.2xc2x0 C. The factors which may influence a person""s body temperature include physical activity, environmental conditions, and even the time of day.
It is also well known that an increase in body temperature is a normal response to a bacterial or viral infection. This change in body temperature occurs because bacteria and viruses cannot survive outside a fairly narrow range of temperatures. Likewise, it is known that cancer cells, HIV (human immunodeficiency virus), and hepatitis virus cannot survive extreme temperatures.
To take advantage of this susceptibility to temperature extremes, it is well accepted in the art that intentionally induced single limb hyperthermia is an acceptable treatment for cancer isolated in limbs. However, it is also known in the art that whole body hyperthermia can cause serious side effects such as increased acidity in the blood and neurological damage. Thus, intentionally induced whole-body hyperthermia has not been feasible to treat cancers which are not isolated in limbs.
For the same reason, intentionally induced whole-body hyperthermia has not been a feasible treatment for bacterial or viral infection. For example, Ginsburg, U.S. Pat. No. 5,486,208, discloses a method and apparatus for controlling a patient""s body temperature by transferring heat to a patient""s blood via a catheter. However, Ginsburg does not address the possible neurological damage that could be caused by the increase in body temperature.
Similarly, Keeling, U.S. Pat. No. 5,476,444 discloses a method for increasing the temperature of the blood extracorporeally. However, by not increasing the temperature of the body itself above 45xc2x0 C., the method of Keeling does not raise the body temperature to a level high enough to kill the viruses, bacteria, or cancer cells. Moreover, like Ginsburg, the method of Keeling does not disclose a method for protecting the central nervous system from neurological damage caused by the increased body temperature.
It is also known in the art that it is desirable to intentionally induce hypothermia for treatment purposes. For example, during cardiac surgery, the body temperature may be reduced to between 18xc2x0 C. and 20xc2x0 C. to allow complete circulatory arrest. However, it is well known that such hypothermia must usually be limited to less than sixty minutes to prevent neurological damage.
Thus, it can be seen that there is a need in the art for a method and device for raising the body temperature above 45xc2x0 C. or lowering the body temperature below 20xc2x0 C. for extended periods of time to allow medical treatment without risking neurological damage.
The present invention, a device for intentionally inducing whole-body hyperthermia or hypothermia in a patient while protecting the central nervous system, has four major components. First, the invention includes a tub for immersing the patient""s body in a solution with a temperature greater than or less than normal body temperature to increase or decrease the patient""s body temperature.
Second, the invention includes a system for circulating the patient""s cerebral spinal fluid. The circulator includes a catheter inserted into the patient""s spinal canal and a pump to withdraw the patient""s cerebral spinal fluid. A heater and cooler control the temperature of the cerebral spinal fluid and a fluid port allows a medical professional to alter the chemical characteristics of the cerebral spinal fluid. Preferably, a thermocouple is provided to automatically control the temperature of the cerebral spinal fluid. In a preferred embodiment, anesthetic is introduced into the cerebral spinal fluid through the fluid port to induce a profound nerve blockade and a calcium-channel blocker and membrane stabilizing agents are introduced to reduce injury to the central nervous system tissues during treatment. A pump reintroduces the cerebral spinal fluid into the patient through a catheter inserted into the patient""s spinal canal.
Third, the invention includes a system for circulating the patient""s central nervous system blood. The central nervous system blood circulator includes input catheters inserted into the patient""s right and left jugular veins and output catheters inserted into the patient""s right and left vertebral arteries and right and left carotid arteries. A pump withdraws the blood from the patient""s central nervous system through the input catheters. A hemodialysis device known in the art controls the chemical characteristics of the withdrawn central nervous system blood and a heater and cooler control the temperature of the withdrawn central nervous system blood. A membrane exchanger known in the art oxygenates the central nervous system blood. The central nervous system blood is passed through a filter to remove blood clots. The pump reintroduces the central nervous system blood into the patient. Preferably, a thermocouple is provided to automatically control the temperature of the central nervous system blood. In a preferred embodiment, anesthetic is introduced into the central nervous system blood through a fluid port to induce a nerve blockade and a calcium-channel blocker and membrane stabilizing agents are introduced to reduce damage to the central nervous system tissues during treatment.
Fourth, the invention includes a device for circulating the blood through the remainder of the patient""s circulatory system. The body blood circulator includes an input catheter inserted into the patient""s femoral vein and an output catheters inserted into the patient""s femoral arteries. A pump withdraws the blood from the patient""s body through the input catheter. A hemodialysis device known in the art controls the chemical characteristics of the withdrawn body blood and a heater and cooler control the temperature of the withdrawn body blood. A membrane exchanger known in the art oxygenates the body blood. The body blood is passed through a filter to remove blood clots. The pump reintroduces the body blood into the patient. Preferably, a thermocouple is provided to automatically control the temperature of the body blood. In a preferred embodiment, anesthetic is introduced into the body blood through a fluid port to anesthetize the patient and induce a nerve blockade and a calcium-channel blocker and membrane stabilizing agents are introduced to reduce damage and injury to the tissues during treatment.
In use, the patient is first anesthetized. The cerebral spinal fluid circulator is connected to the patient""s spinal canal and the central nervous system blood circulator and body blood circulator are connected to the patient""s circulatory system as described above. The cerebral spinal fluid, central nervous system blood, and body blood are circulated and treated as described above. The patient is then immersed in a solution to raise or lower the body temperature. Preferably, the cerebral spinal fluid and central nervous system blood are maintained at a desired target temperature for treatment. The induced whole-body hypothermia or hyperthermia is maintained for a predetermined period of time. The temperature of the solution is then gradually changed to near normal body temperature.
It is an object of the present invention to provide a method and device for inducing hypothermia or hyperthermia while protecting the central nervous system from damage caused by extreme temperatures.